Bad service

I took a credit card last year around October 2020 , somehow nedbank decided to open two accounts on credit cards , however I was given one . Just because of someone did not do their job by not cancelling the other credit card that was opened by mistake . Now I’m getting calls left right and centre that I am owing something that was not even requested by me ! I have been with nedbank for more than 6 years and I have a very good record with them . Now this will affect my credit score just because of someone’s negligence I need this sorted out and a letter send to clear my name I sick of this really